Thread: While loop Problem Please Help!

I think you have correctly identified the problem: the animation takes place in code (a while loop, but it could be anything) that does not complete until *after* some significant event has taken place. Consequently you never get to find out about and react to that event.

We can think about motion in two ways. It can be thought of as a continual change of position, but equally it can thought of as a number of very small steps in sequence but, in terms of code, independent of the others. The solution to the problem is to write code that moves the arrow by just one coordinate unit. That will complete very quickly and give you time to check whether a monster has been hit etc.

Of course this code has to be called lots of times. And you don't want to call it within your code, because that will leave you with pretty much the same problem. So what you do is create a Timer with a callback that will get called from outside your program every 50 milliseconds or so. This callback is what moves the arrow's coordinates by just one coordinate unit, checks for a monster being hit (and reacts) and schedules a repaint of the screen.

See How to Use Swing Timers in Oracle's Tutorial.